Water craft, especially small water craft designed for personal or small scale use, are typically driven by either a manual propulsion means (e.g., oars and paddles), one or more sails, a propeller or jet system coupled to a power source or an air-drive system resembling a large fan mounted on the back of the boat (i.e., an air boat).
The different drive systems are typically used for different purposes or are suitable for different types of waterways. For example, the operator of a canoe or a small rowboat may choose to use paddles or oars for exercise, because they are quite or because they are inexpensive and require little or no maintenance. Boats that are wind powered (i.e., sailboats) require skill to operate and are at the mercy of the wind.
Airboats are specially designed boats that are used most often in waterways which contain a large amount of under water plant growth and/or are shallow or have shallow areas. Airboats are ideal for this because they have no moving parts below the water that may get tangled on the under water plants or hit bottom in shallow areas. However, airboats are noisy since the propulsion means is a large fan mounted on the back of the boat. Also, the fan propulsion system takes up a considerable amount of space on the boat thereby limiting its use as a vehicle to transport persons or cargo.
The operator of a canoe and, especially, a rowboat may choose to use an outboard motor. Some of the advantages of using a motor are that the operator may travel at a greater speed and expend less energy than when using oars or paddles. Also, they are not at the mercy of the wind for propulsion. However, outboard motors suffer from the problem of getting tangled up in water plants or other debris that may be in the water. Often times boat operators must stop and untangle the propeller on the boat before they can continue. Prior art designs that tried to solve the problem of getting tangled also resulted in a reduction in power or thrust for a similar sized motor.
What is needed is a propulsion system for boats that can be used by the typical small boat operator that is more dependable that wind power, requires less energy that manual propulsion means and is designed 1) to resist being tangled by under water plants and other water hazards, 2) not cause motor stalling or other motor problems in the event that the drive means is impeded and 3) create adequate thrust for satisfactory propulsion of the water vehicle.